National Academies Press: OpenBook

Risk-Based Construction Inspection: A Guide (2023)

Chapter: Appendix D - Illustrative Case Study Application of RBI Framework to Optimize Inspection Resources

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Suggested Citation:"Appendix D - Illustrative Case Study Application of RBI Framework to Optimize Inspection Resources." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
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Suggested Citation:"Appendix D - Illustrative Case Study Application of RBI Framework to Optimize Inspection Resources." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
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Suggested Citation:"Appendix D - Illustrative Case Study Application of RBI Framework to Optimize Inspection Resources." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
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Suggested Citation:"Appendix D - Illustrative Case Study Application of RBI Framework to Optimize Inspection Resources." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
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Suggested Citation:"Appendix D - Illustrative Case Study Application of RBI Framework to Optimize Inspection Resources." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
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Suggested Citation:"Appendix D - Illustrative Case Study Application of RBI Framework to Optimize Inspection Resources." National Research Council. 2023. Risk-Based Construction Inspection: A Guide. Washington, DC: The National Academies Press. doi: 10.17226/27099.
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D-1   A P P E N D I X D Illustrative Case Study—Application of RBI Framework to Optimize Inspection Resources A case study project from Kansas DOT was conducted to verify and illustrate the application of a project- level RBI framework to optimize inspection resources based on risk levels for inspection activities. Project data were collected from Kansas DOT Construction Management System (CMS). The CMS provided data on the project description (e.g., cost, duration, quantities) and different construction operations. This case study project involved the construction of 5.8 miles of roadways with a total cost of $11.85 million. The core construction operations included earthwork, subgrade and base course, and hot mix asphalt (HMA) pavement. Stage 1: Determination of inspection activities and resources Table D-1 shows a sample of 14 inspection activities associated with earthwork, subgrade and base course, and HMA pavement with an estimated duration of each activity. For example, for the earthwork operation, there are five core inspection activities, including (1) lift thickness with 1.5 hours required for inspection; (2) foundation preparation with 2.0 hours for inspection; (3) placement inspection with 1.5 hours; (4) compaction control with 2.5 hours; and (5) drainage work with 2.5 hours. Table D-1 also shows an example of the inspection schedule for two days. Day (X) includes 11 activities to be inspected, and Day (Y) has seven activities to be inspected. Two full-time in-house inspectors are available for the project, with a total of 16 hours/day. The project inspection staff needs were determined using Table 4-1, where three construction inspectors (mean = 2.65) are required with a total of 24 inspection hours/day. Accordingly, there is a shortage of approximately eight inspection hours/day.

D-2 Risk-Based Construction Inspection: A Guide Stage 2: Risk-based prioritization of inspection activities Table D-1. Sample case project inspection activities. Inspection Schedule Inspection Activity (estimated duration in hrs.) Sample of inspection activities required • Earthwork: Lift thickness (1.5); Foundation preparation (2.0); Placement inspection (1.5); Compaction control (2.5); Drainage work completion (2.5) • Subgrade/Base Course: Base patching (2.5); Lift thickness (2.0); Compaction control (2.5); Placement inspection (1.5); Surface tolerance (2.5) • HMA: Coat and surface preparation (1.5); Dimensions, thickness and grade (1.5); Surface smoothness (2.0); Density (nuclear gauge or other) (2.5) Day (X) • Earthwork: Lift thickness; Foundation preparation; Placement inspection; Compaction control; Drainage work completion • Subgrade/Base Course: Base patching; Lift thickness; Compaction control; Placement inspection; Surface tolerance • HMA: Coat and surface preparation Day (Y) • Subgrade/Base Course: Base patching; Lift thickness; Compaction control; Surface tolerance • HMA: Coat and surface preparation; Dimensions, thickness and grade; Density (nuclear gauge or other) Figure D-1 summarizes the result of the risk-based prioritization process of the 14 activities. Figure D-1 shows that two activities lie in Tier 1 (high risk); 10 activities lie in Tier 2 (medium risk); and two activities lie in Tier 3 (low risk). The compaction control of earthwork is the highest risk activity with CI = 10.2, while the placement inspection of earthwork is the lowest risk activity with CI = 2.0. Figure D-1. Risk composite index of 14 inspection activities. Stage 3: Inspection workload determination 10.2 6.8 6.6 6.0 2.0 6.6 6.6 5.8 4.6 2.4 9.2 6.4 4.4 4.2 0.0 2.0 4.0 6.0 8.0 10.0 12.0 Compaction control Drainage work Foundation preparation Lift thickness Placement inspection Base patching Compaction control Surface tolerance Placement inspection Lift thickness Density Dimensions and thickness Coat/surface preparation Surface smoothness Ea rth w or k Su bg ra de /B as e C ou rs e H M A Composite index (CI) In this step, the two scenarios have been examined to allocate inspection staff when there is a significant, moderate, or little concern about staff shortage. It is worth noting that a spreadsheet was created to automate the calculation process and save time. Figure D-2 summarizes the results of the calculation process. In the first scenario of the day (X), the 11 activities were ranked based on their CIs. The cumulative duration of the activities was added in a descending manner from the highest CI to the lowest CI. The resulting cumulative duration of the 11 activities was 22.5 hours, more than the 16 available hours of two full-time inspectors. Thus, the first seven activities with a cumulative duration of 16 hours have been selected for inspection. Out of the seven activities, one activity, compaction control of earthwork, belongs to Tier 1, and six activities belong to Tier 2. The six activities include lift thickness, drainage work, base patching, compaction control, foundation preparation, and surface tolerance of the base course. Figure D-2 shows that the four inspection activities (e.g., placement inspection of base course, coat and surface preparation, lift thickness of base course, and placement inspection of earthwork) that were not included for inspection had a low CI risk score (Tiers 2 and 3).

Illustrative Case Study—Application of RBI Framework to Optimize Inspection Resources D-3   Figure D-1. Risk composite index of 14 inspection activities. Stage 3: Inspection workload determination 10.2 6.8 6.6 6.0 2.0 6.6 6.6 5.8 4.6 2.4 9.2 6.4 4.4 4.2 0.0 2.0 4.0 6.0 8.0 10.0 12.0 Compaction control Drainage work Foundation preparation Lift thickness Placement inspection Base patching Compaction control Surface tolerance Placement inspection Lift thickness Density Dimensions and thickness Coat/surface preparation Surface smoothness Ea rth w or k Su bg ra de /B as e C ou rs e H M A Composite index (CI) In this step, the two scenarios have been examined to allocate inspection staff when there is a significant, moderate, or little concern about staff shortage. It is worth noting that a spreadsheet was created to automate the calculation process and save time. Figure D-2 summarizes the results of the calculation process. In the first scenario of the day (X), the 11 activities were ranked based on their CIs. The cumulative duration of the activities was added in a descending manner from the highest CI to the lowest CI. The resulting cumulative duration of the 11 activities was 22.5 hours, more than the 16 available hours of two full-time inspectors. Thus, the first seven activities with a cumulative duration of 16 hours have been selected for inspection. Out of the seven activities, one activity, compaction control of earthwork, belongs to Tier 1, and six activities belong to Tier 2. The six activities include lift thickness, drainage work, base patching, compaction control, foundation preparation, and surface tolerance of the base course. Figure D-2 shows that the four inspection activities (e.g., placement inspection of base course, coat and surface preparation, lift thickness of base course, and placement inspection of earthwork) that were not included for inspection had a low CI risk score (Tiers 2 and 3).

D-4 Risk-Based Construction Inspection: A Guide Figure D-2. Prioritized daily inspection activities with workload durations. Similarly, in the second scenario of the day (Y), the seven activities were ranked according to their CIs with a cumulative duration of 15 hours, less than the 16 available hours of two full-time inspectors. Thus, a total of seven activities were selected for inspection. Out of the seven activities, one activity (i.e., density of HMA) was in Tier 1; five activities (i.e., base patching, compaction control of base course, dimensions and grade, surface tolerance of base course, and coat and surface preparation) were in Tier 2; one activity (lift thickness of subgrade/base) was in Tier 3. The result of this prioritization process was valid and supported by the project inspection documentation.

Abbreviations and acronyms used without de nitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America’s Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration GHSA Governors Highway Safety Association HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S. DOT United States Department of Transportation

Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 ADDRESS SERVICE REQUESTED ISBN 978-0-309-69867-2 9 7 8 0 3 0 9 6 9 8 6 7 2 9 0 0 0 0 N C H RP Research Report 1039 Risk-Based Construction Inspection: A G uide

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Due to budget cuts and reduced experience levels of inspectors and engineers, state departments of transportation (DOTs) have implemented risk-based strategies to achieve greater efficiency in construction inspection. These strategies include prioritizing inspection based on inherent risks related to construction operations, using emerging technology applications to save time, and accepting certification and contractors' test results to offset shortages of experienced inspection resources.

NCHRP Research Report 1039: Risk-Based Construction Inspection: A Guide, from TRB's National Cooperative Highway Research Program, discusses the importance of construction inspection and aims to assist state DOTs and the U.S. Federal Highway Administration in meeting quality standards.

Supplemental to the report are NCHRP Web-Only Document 344: Risk-Based Construction Inspection: Conduct of Research Report and an Inspection Risk Assessment Questionnaire.

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